Reverting Gemma checkpointing logic

[SalmanMohammadi]

Context

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#1062 #1122

Changelog

Reverting #1064, leaving Gemma checkpointing test in.

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[pytorch-bot]

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[joecummings]

@SalmanMohammadi Can you confirm that you can train a model for like 5 steps and then save and it works?

[ebsmothers]

@joecummings I patched the changes on my end and ran tune run --nnodes 1 --nproc_per_node 4 lora_finetune_distributed --config gemma/7B_lora max_steps_per_epoch=5. Can confirm it now errors out at the PEFT weight conversion (i.e. this PR resolves the previous issue with lm_head.weight as it makes it past the saving of the model). So based on that I am gonna merge, we can work on a separate PR for the PEFT weight saving issue.